1. Field of the Invention
The present invention relates to a reinforcing structure for a body frame of a vehicle.
2. Description of Related Art
In general, the body frame of a vehicle is formed by various framework members each having a closed section, for example, pillars, side members, cross members, side sills, etc. In assembling, these framework members are connected with each other by means of welding etc. In order to enhance rigidity of the assembly while reducing its weight, it has been attempted to fill up the closed section of the framework member with foaming urethane. Alternatively, it has been attempted to insert a reinforcement into the closed section of the framework member (see Japanese Patent Application Laid-open Nos. 2001-8840 and 11-235963).
Additionally, Japanese Patent Application Laid-open No. 2001-180518 discloses a reinforcing structure for body frames of an automobile. In this reinforcing structure, a framework member as a constituent of a vehicle frame is formed by an outer member having a hollow (closed) section and a reinforcement inside the outer member. By the integral forming method, the reinforcement is shaped so as to overlap the whole inside of the outer member, thereby reinforcing it effectively and lightly.
In the former structures adopting the foaming urethane and the reinforcement, there is a tendency of increasing a charging amount of the foaming urethane and a thickness of the reinforcement in order to ensure sufficient reinforcing effect, causing a weight of the vehicle body to be increased.
In the latter structure, as the reinforcement is configured so as to follow an uneven inside profile of the outer member, the strength distribution of an integrated element (i.e. the outer member and the reinforcement) is still unchanged in comparison with that of the outer member though its strength is improved by the addition of the reinforcement. Therefore, as to the position of folding deformation, there is no difference between the outer member with the reinforcement and the outer member with no reinforcement. That is, despite the whole area of the outer member being covered with the reinforcement, it merely has effect to reinforce such a deformable part(s) of the outer member, exhibiting an ineffective reinforcing effect.
In such a situation, it is an object of the present invention to provide a reinforcing structure for a body frame, which can provide the body frame with a sufficient reinforcing effect without increasing the weight of the vehicle body.
According to the present invention, the above-mentioned object is accomplished by a reinforcing structure for a body frame of a vehicle, comprising:
a framework member having two wall members adjacent to each other to provide a peripheral wall of the framework member with a double wall structure; and
an adjusting mechanism for adjusting respective buckling-mode waveforms of the two wall members to be different from each other.